@article{DE_1991_27_4_a10,
     author = {N. I. Popivanov and M. Schneider},
     title = {A boundary value problem for the nonlinear {Tricomi} equation in three dimensions},
     journal = {Differencialʹnye uravneni\^a},
     pages = {648--655},
     publisher = {mathdoc},
     volume = {27},
     number = {4},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1991_27_4_a10/}
}